In general, a “satellite” is any object that orbits a planet or other celestial body. However, the term “satellite” is more commonly used in the art to refer to a manmade object designed to orbit Earth and carry out one or more specific functions.
While satellites were initially used to perform functions associated with space exploration and military defense, satellites are now commonly used by various entities to perform non-space and non-military functions. For example, satellites are used to observe weather conditions, provide global positioning, assist in search and rescue missions, and receive and broadcast television, radio, and phone communications.
Although the number of satellites in orbit continues to increase, the costs associated with building and launching satellites are significant. Accordingly, it is important to keep a satellite in orbit as long as possible so as to reduce the rate at which the satellite needs to be replaced. In an effort to maintain satellites in orbit, various techniques are used to service satellites while in orbit. For example, techniques are implemented to replenish a satellite's fuel or power supply and repair damaged or outdated components. One such technique involves the use of a space transportation vehicle (e.g., the United States Space Shuttle) and/or crew aboard the vehicle to acquire and service the satellite.
Facilitating the acquiring of an orbiting satellite is heavily dependent on the size of satellite. In other words, the design of a “docking” mechanism for capturing a satellite in orbit depends on the size of satellite intended to be obtained using the docking mechanism. A “large” satellite weighs over 1000 kg; a “medium” or “small” satellite weighs 500-1000 kg; a “mini” satellite weighs 100-500 kg; a “micro” satellite weighs 10-100 kg; a “nano” satellite 1-10 kg; a “pico” satellite weighs 0.1-1 kg; and a “femto” satellite weighs less than 100 g.
Large and medium/small satellites usually require a host vehicle with a relatively large payload for servicing. The actual docking of such a satellite to the host vehicle generally involves (i) the use of satellite thrusters to maneuver the satellite in a particular position and (ii) a robotic arm to “grasp” and orient the satellite in the payload of the host vehicle. Docking mechanisms for smaller satellites are disclosed in: U.S. Patent Publication No. 2003/0192995 A1, showing a harpoon mechanism that, when triggered, engages a target in such a way that it can not be pulled out of a receptacle of a receiving structure; U.S. Patent Publication No. 2004/0245404 A1, showing an apparatus having a container with a chamber therein and a motorized closing mechanism for driving a door to open or close an opening of the container into the chamber; U.S. Pat. No. 6,484,973, showing a remote cockpit system for allowing human control during proximity operations; U.S. Pat. No. 6,845,303, showing maneuvering an active vehicle in accordance with data transmitted from a target vehicle to the active vehicle, the data representing relative position and velocity between the target vehicle and the active vehicle; U.S. Pat. No. 6,866,232, showing an automated docking system having a plurality of antennas on each of a target vehicle and a chase vehicle; U.S. Pat. No. 6,840,481, showing an adjustable multipoint docking system having a plurality of adjustable grasping jaws; U.S. Pat. No. 4,664,344, showing a technique for capturing an orbiting spacecraft by attaching a grapple fixture; U.S. Pat. No. 5,449,211, showing a two-fault tolerant electromagnet attachment mechanism which is adapted for interfacing with the manipulator arm of a remote manipulator system and effecting the grapple of a target object by the attractive force of the magnetic field of one or more electromagnets; U.S. Pat. No. 6,275,751, showing a smart docking surface consisting of closely spaced cantilevered sensor/actuator structures capable of precisely repositioning an object having a ferromagnetic surface in contact with the smart docking surface; U.S. Pat. No. 6,354,540, showing a fully androgynous, reconfigurable closed loop feedback controlled low impact docking system with load sensing electromagnetic capture ring; and U.S. Pat. No. 4,381,092, showing a boom formed by spring biased telescoping tubes that is gimbaled at one end to a docking or probe space vehicle and at the opposite end to an electromagnet probe with the gimbaled joints spring biased to axially align the assembly.